Ok, with all the talk of header failure, I decided to pull mine and test them. I plugged all the holes but one. I hooked up the garden hose to it. Made sure the air was bleed out of the header and filled it up. A house will normally run 40 to 70 pounds of water pressure. Will this work and is that enough pressure to show a leak???

proper test would be to get a pressure guage and a ball valve, fill it as much as possible with water or air pressure if you like to around 70 to a 100psi.

close the valve and let it sit for say four hours or more.

assuming not in the sun the pressure should stay the same, if it doesnt, get some soapy water and start checking for leaks.

you could also use a die penetrant test kit.

Could also pressurize and use a Tupperware bin for quick water dunk tank test.

yes that will work fine...inspect the welds around the inner pipe close top the cylinder head for cracks or rust stains..

That's how I did mine. The water pressure in your boat will pry never hit 70lbs anyways

Thanks for the replies. Checked the house water pressure, a good solid 60 lbs. The good news is the inside of all were bone dry. The bad news is there was a weeper on the outside of two tubes. There was also some scale ( looks like rust ) inside two tubes. Any thoughts???

Thanks